Control of UV deterioration by incorporation of N-(benzimidazol-2-yl) arylcarboxamides into a UV sensitive substance

ABSTRACT

This invention relates to compositions containing N(benzimidazol-2-yl)arylcarboxamides as ultraviolet (UV) light absorbers. The compounds are useful to protect UV sensitive materials, particularly plastic compositions, or ingredients thereof such as dyes, anti-microbial agents, or plasticizers from attack by ultraviolet light. The compositions are suitable for those uses where UV protection is required only for short periods of time, for example in sun tan lotions, as well as for uses which require protection for extended periods of time.

ARYLCARBOXAMIDES INTO A UV SENSITIVE SUBSTANCE lnventor:

[63] Continuation-impart of Ser. No. 758,601, Sept. 9,

I968, abandoned.

[52] US. Cl. 252/300; 260/45.8 N; 260/309.2

[51] Int. Cl. F21V 9/06 [58] Field of Search 252/300, 403; 260/45.8 N,260/309.2

[56] References Cited UNITED STATES PATENTS 2,985,661 5/1961 Hein et al.252/300 X United States Patent 1191 1111 3,907,700 Grier Sept. 23, 1975[5 CONTROL OF UV DETERIORATION BY 3,218,276 11/1965 Ringwald et al.260/45.8 N x INCORPORATION OF 1 3,255,202 6/1966 Johnson 260/45.8 N X3,336,191 8/l967 Craig et al. 260/309.2

N (BENZIMIDAZOL 2 YD 3,401,173 9/1968 Chow 260/3092 PrimaryExaminer-Benjamin 1R. Padgett Assistant ExaminerR. E. Schafer Attorney,Agent, or Firm-Edmunde D. Riedl; .1. Jerome Behan; Frank M. Mahon [57]ABSTRACT This invention relates to compositions containing N-(benzimidazol-Z-yl)arylcarboxamides as ultraviolet (UV) light absorbers.The compounds are useful to protect UV sensitive materials, particularlyplastic compositions, or ingredients thereof such as dyes,anti-microbial agents, or plasticizers from attack by ultraviolet light.The compositions are suitable for those uses where UV protection isrequired only for short periods of time, for example in sun tan lotions,as well as for uses which require protection for extended periods oftime.

6 Claims, No Drawings CONTROL OF UV DETERHORATHON BY ENCORPQRATION OFN-(BENZTMIDAZUL-Z-YL) Al lYLCAlRBOXAlQ/HDES llNTO A UV SENSl'llll /ESUBSTANCE This application is a continuation-in-part of prior copendingapplication Ser. No. 758,601, filed Sept. 9, 1968 now abandoned.

This invention relates to compositions containing selective lightarresters which exhibit high absorption ca pacities for incidentultraviolet radiation. More partic ularly this invention relates tocompositions containing N-(benzimidazol-2-yl)aryl or (heteroaryl)-carboxamides as ultraviolet absorbers.

Ultraviolet radiation can interact with a variety of materials toproduce deleterious effects. Fortunately, a

good proportion of this energy originating from the sun is removed bythe earths atmosphere. In the ultraviolet region, which comprises aboutof the total incident solar energy, the energy content decreases inintensity from 400 millimicrons to practically zero at 290 millimicrons.However, the lower wave length region of this energy segment is aprimary factor in the rapid destruction of many substances includingplastics, wood, textiles. leather, coatings, etc. For the protection ofthese materials against degradation certain ultraviolet lightabsorbingcompounds, commonly called U.V. absorbers, and characterized by havingpeak absorption in the range of from about 300 350 millimicrons arefrequently employed.

it has been discovered that benzimidazoles substituted in the 2-positionby an aroylamino or hcteroaroylamino group are capable of being highlyefficient absorbers of UV energy in the region of 300-350 ,u, along withan inherent ability to dissipate harmlessly the acquired energy withoutaffecting the exposed system or components contained therein, andwithout self destruction.

The N-(benzimidazol-2-yl)arylcarboxamide or N-(bcnzimidazol-Z-yl)heteroarylcarboxamide compounds which find novel usein this invention may be represented structurally by the formula I belowin this formula R represents an aromatic radical having l-3 nuclei,including a carbocyclic aryl radical such as phenyl, biphenyl. naphthyl,anthryl, phenanthryl, and the like, and a heteroeyelie aryl radical suchas fu ran, thiophene, pyridine, pyridazine, pyrimidine, pyra zine,quinoline, isoquinoline, acridine, phenanthridine, phenazine,phenoxazine, phenthiazine, coumarone,

benzothiophene, indole, pyrazole, imidazole. thiazole,

oxazole, triazole, carbazole and the like. Specifically excluded fromthe invention are aliphatic acid amides of Laminobenzimidazole (where R,is alkyl); they fail to protect against UV.

in addition R may be attached to the carbonyl through a vinyl group-(CH=CH Representative compounds of this type are N(benzimidazol-2- yl)cinnamamide and 2-( 2- furanacrylyl)aminobenzimidazole. These compoundswill prevent the development of additional color in sensitive plasticswhen exposed to UVJight Without imparting significant color to theplastic initially. This useful result is accomplished because thecinnamamide compounds are so highly efficient that relatively lowconcentrations of less than 0.5% by weight need to be employed.

R represents hydrogen, alkanoyl, alkenyl, benzoyl. halobenzoyl,alkoxybenzoyl, alkoxycarbonyl, benzoyl. alkyl, phenyl, or aralkyl.

The light absorbing compound may also be aN-(benzimidazol-Z-yl)phthalimide, or a phthalamide such as N,N-bis(benzimidazol-Z-yl)phthalamide, N,N bis(benzimidazolZ-yl)isophthalamide,or N,N- bis(benzimidazole-2-yl)terephthalamide, where two carboxy groupsof a benzene polycarboxylic acid form amides with the 2-amino group ofthe 2 aminobenzimidazole, as is more fully described on flow sheet I.

The benzene and/or heterocyclic rings present in any of the abovedescribed compounds, including the benzene ring of the benzimidazole, acarbocyclic or heterocyclic aryl ring present at R and the benzene ringof any phthalimide or phthalamide compound, may be unsubstituted, orsubstituted by one or more of the following groups: alkyl, which may bestraight or branched chain, alkenyl, aryl especially phenyl, phenalkylor naphthyl, heteroaryl, halogen, nitro, hydroxy, alkoxy, phenoxy ornaphthoxy, amino, alkylamino, dialkylamino, phenylamino, phenalkylamino,sulfo, carboxy, alkoxycarbonyl, alkanoyl or benzoyl.

Among the compounds which can be utilized are: N-(5-dodecyloxybenzimidazol-Z-yl)-2-carboxamidonaphthalene; N-(4-phenylbenzimidazol-Z-yl)-4- phenylbenzamide; N-(l-methyl-4-phenylbenzimidazol- 2yl)-3toluamide;N(S-dimethylaminobenzimidazol- Z-yl)-4-nitrobenzamide;N(benzimidazol-2-yl)-4- carboxamidoimidazole;N-(4-t-butylbenzimidazol-2- yl)-3-carboxamidothiophene;N-(benzimidazol-Lyh- 3,S-di-tert-butylbenzamide; N-(benZimidazol-2-yl)-4benzyll -carboxamidonaphthalene; N-(S-methoxybenzimidazol-Z-yl)-4-toluamide; N-(4-phenoxybenzimidazol-2-yl)-4-carboxamidothiazole; N-(1-acetyl-benzimidazol-Z-yl)benzamide; N-(benzimidazol-Z-yl)-3-sulfobenzamide; N(benzimidazol2-yl)-3-carboxybenzarnide; N-(oenzirnidazol-Z-yl)-8-carboxamidoquinoline; N- (benzimidazoLZ-yl)-3-carboxamidoquinoline; N- (benzimidazol-Z-yl)A-carboxarnidopyridine;N-(5,6- dimethylbenzimidazol-Z-yl)--3-chlorobenzamide; N-(benzimidazoLZ-yl )-4-hydroxyethylbenzamide; N (benzimidazol-Z-yl)-4-acetylbenzamide; N- (4sulfobenzimidaZol-2-yl)-3-chlorobenzamide;N-(S- sulfobenzimidazol-Z-yl)-4-phenylbenzamide; N-[5-(lnaphthyl)benzirnidazoLZ-yll-4-chlorobenzamide; N- [4-( 3-thienyl)benzimidazol2-yl]-benzamide; N-( 5-aminobenzirnidazol-Z-yl)-otoluarnide;N-l4-(npropylamino)benzimidazol-ZZ-yll-3-ethylbenzamide;N-[5-(phenylamino)benzimidazoLZ-yl1-4- methoxybenzamide; l l-[ 4-4benzylamino )benzimidazol- 2-yl]napthalene-2-carboxamide; N-(S-nitrobenzimidazol-Z-yl )benzamide; N-[ llcyanobenzimidazol-2-yll-p-nitrobenzamide; N-( 5,6- dimethylbenzimidazol-Z-yl )-o-toluamide;N-( 5 ,6- dimethylbenzimidazol-Z-yl)-p-toluamide; N-(S- acetamido)benzimidazoLZ-yl )benzamide; N-( 5- yl)-4-hydroxybenzamide;N-(5-methylbenzimidazol-2- yl)-2-phenoxybenzamide; N-(5,6-dimethylbenzimidazol-Z-yl)-4-amino-2- methylbenzamide;N-(benzimidazol-2-yl)-3- methylaminoisonicotinamide;N-(benzimidazol-2-yl)- 3-benzylbenzamide;N-(4-methylbenzimidazol-Z-yl)-4- butoxycarbonylamino benzamide;N-(benzimidazol-2- yl)-3-sulfobenzamide;N-(benzimidazol-Z-yl)-2-benzoylbenzamide;N-(benzimidazol-2-yl)-4-benzoylbenzamide; N-( 5-chlorol-methoxycarbonylbenzimidazol- 2-yl)benzamide;N-[4-(4-chlorophenyl)benzimidazol- 2-yl]benzamide;N-(S-aminobenzimidazol-Z- (Il l 3 4benzamido)benzimidazol-Z-yl)-benzamide; N-(S- yl)benzamide;N-(benzimidazol-Z-yU-aanthranamethoxybenzimidazol-2-yl)benzamide; N-(4-mide. lauroyloxy)benzimidazol-Z-yl)benzamide; N-(5,6- It is known thatZ-aminobenzimidazoles show no sigdimethylbenzimidazol-2-yl)-o-toluamide;N-(5,6- nificant absorption above 300 millimicrons and 2-aroyldimethylbenzimidazol-2-yl)p-toluamide; N-(S- 5 orZ-heteroaroyl-substituted benzimidazoles are rapidlyacetamido)beHZimidaZOI-Z-YI)bel'llamide; degraded by UV light. Forexample, in a series of conbenlamido)beIIZimidaZOI-Z-YI)benzamide;ventional tests utilizing plastic films as substrate, 2-benzamido)benZimidazl-2-yl)benzamide; benzoylbenzimidazole incorporationin these films mCthOXYbQEZimidaZOI-Z-YI)benlamide; caused greater colorformation upon exposure to UV lauroyloxy)-benzimidazol -yl) z m lightthan the untreated control film. Similar observa-(benzimidazol-Z-yl)-2-benzoylbenzamide; N- tions were noted for other2-aroy1 and heteroaroyl- -y y i substituted benzimidazoles. Evidently,the compounds chloro-l-methoxycarbonylbenzimi azol-2- undergophotochemical transformation to produce yl)benzamide;N-[4-(4-chlorphenyl)benzimidazol-2 highly colored end-products.Surprisingly, the interpoyllbenzamide; d lsition of a carbonylaminogroup between the 2-position yl)benzamide; N-(benzimidazol-Z-yl)-a-anthranamide; of the benzimidazole and the aryl orheteroaryl substity y -y uent provides a significant increase in UVsbsorption pivaloylbenzimidazol-2-yl)benzamide; efficiency over2-aminobenzimidaz'ole, especially in theStearoylbenzimidazolz-yl)benzamide; region critical to the stabilizationof many substrates, acrylylbenzimidazol-z-yl)benzamide; and the2-aroylaminobenzimidazoles withstandsucbenzoylbenzimidazol-Z-yl)-benzamide; N-( l-pf ll h energy absorption.tolllylbenzimidMOI-2'31)benzamide; One hypothesis which may help toexplain the ability mesitoylbenzimidazol-2'3!)benzamide; of thecompounds of this invention to dissipate UVenbutylbenzimidazol-Z-yl)benzamid ergy in the harmless manner centersupon the possibiloctylbenzimidazol'z'yl)benzamide; ity of formation of achelate structure, which can arise Pheny1benZimidaZ01-2-y1)benzamide; byenolization of the amide at least transiently. Themethoxycarbonyl-Z-yl)benzamide; N-(benzimidazol-Z- postulated h latestructure (I) in which R is aryl or heteroaryl may provide the resonancepath for energy release. However, we do not wish to be bound to such aproposed mechanism. The theory gains support from data showing that awide variety of substituents can be introduced at R, and also at thebenzo portion (4-, 5-, 6- and 7-position) of the benzimidazole ringsystem without causing loss of utility and performance.

Table I, listing some 2-aroylaminobenzimidazoles, indicates howparticular substituents comprising the acid group of the amide canproduce absorption maxima over the useful range and having highefficiencies.

Table I UV ABSORBERS Table l-Continued o CH=CH- (isophthaloyl, di)

, in ethyl alcohol for max. (m

1% lem all compounds except 11 and 13 (in dimethylformamide).

The heteroaroylaminobenzimidazoles are also surprisingly effective,useful screening agents. They, too, absorb energy in the critical range,that is, between 300 and 350 millimicrons with a high order ofefficiency comparable to the aroyl derivatives outlined in Table -2.Whereas the parent heterocycle, for example, pyri- 'dine or thiazole isunstable to UV-light, especially when joined directly to the 2-carbon ofbenzimidazole, the carboxamido derivatives, for example, 2-nicotinamidobenzimidazole and 2-( thiazole-4- carboxamido) benzimidazolegive significant protection to sensitive polymer systems from thedegradative effects of UV-light energy.

The advantages of such a group of compounds over the prior art becomeespecially important because there is a significant increase instability to air oxidation by elimination of aorthohydroxy-substituted-phenyl requirement, a greater heat and chemicalstability based upon the relatively resistant aroyland heteroaroylamidelinkage, and increased compatabilities with a variety of substratesystems.

Another unexpected property found is that, although the compounds ofthis invention are generally soluble in alkaline solution, the solutionsshow no absorption of light in the visible region, unlike the2-hydroxyphenyl-containing products of the prior art. Still another mostuseful characteristic is the ability to prepare these compounds incompletely colorless condition. As amides of Z-aminobenzimidazole, tlheydissolve in strongly acid media without color formation as well.Precipitation from such media, frequently merely by diluting thesolution with water, produces snow-white products.

Another significant advantage of the compounds of this invention lies intheir low order of volatility. Evidently the amide linkage in these 2-aminobenzimidazole derivatives imparts relatively high resistance tovaporation by heat. These compounds can be subjected to temperatureswell above those which most plastics and other light-sensitive materialsare subjected to during processing, that is, from F to 400F, withoutvolatilization.

in one procedure for preparing the aroylamino-andheteroaroylaminobenzimidazoles a 2 aminobenzimidazole is reacted with anacid anhydride of an aromatic or heterocycle aromatic nucleus, the acylradical of the anhydride becoming the acyl substituent on the aminoradical of the benzimidazole. This process may be pictured structurallyas follows:

I substituted as defined on page 3. However, additional substituentscapable of reacting with anhydrides such as hydroxyl, amino, andmercapto should first be blocked with reagents well known to thoseskilled in the art before reaction with anhydride. Reactions such asacylation, benzylation, and the like can be employed. After reaction ofthe Z-aminobenzimidazole with the anhydn'de, blocking groups can beremoved from substituents if desired. In this particular process,essentially equimolar amounts of the two reactants are brought togetherin a suitable solvent medium. It is preferred to employ a basic solvent.such as pyridine, or one of the picolines. For best results, thereaction is brought about at elevated temperatures of about 50l00C. for/25 hours. The desired 2- acylaminobenzimidazoles may then be recoveredby techniques known to those skilled in the art.

Among the compounds which are readily prepared in this manner are:2-benzamidobenzimidazole, 2- phthalimidobenzimidazole in which theequivalent anhydride structure, that is, the imide is still retained inthe end-product, 2-(2-furoylamino)-benzimidazole, N-(5,6-dichlorobenzimidazol-2-yl)benzamide and N-(benzamidazol-Z-yl)-4-methoxybenzamide. The 2- phthalimidobenzimidazoleserves as a useful intermediate to prepare 2-benzamidobenzimidazoles inwhich the benzoyl moiety is substituted in the 2- or o-position with acarboxylgroup. The substituent in this position can be as an ester or anamide, as well as a free carboxyl group. Esters result upon reaction ofthe phthalimido compoundwith alcohols or phenols, and amides are theproducts of reaction with primary and secondary amines.

A second procedure involves the reaction of an aroyl or heteroaroylhalide with Z-aminobenzimidazole, preferably in a basic medium such aspyridine or quinoline. Usually, heating at 100C for /25 hours issufficient to convert the acyl halide to the corresponding amide. Thereaction mixture is generally quenched in water to precipitate theamide. The pyridine HCl reaction product remains soluble in the water.

The reaction of an aroyl or heteroaroyl halide with a2-aminobenzimidazole can also be conducted in chloroform withtriethylamine as the HCl acceptor at reflux temperatures for about 2-6hours. Approximately stoichiometric quantities of reactants are usedwith an excess of triethylamine. Each of the two components of sea, c

the reaction can be substituted as defined for R R as described abovefor the procedure using the aroyl or heteroaroyl acid anhydride.

Compounds prepared in this way are N- (benzimidazole-Z-yl)-4-biphenylcarboxamide; N,N bis( benzimidazol-Z-yl )-isophthalamide,N,N

bis( benzimidazol-2-yl )-terephthalamide; 2-(nicotinamido)benzimidazole; 2-(thiazole-4-carboxamido )benzimidazole,and 2-( B- naphthoyl )aminobenzimidazole.

Compounds having an alkyl or aryl group at the N nitrogen of thebenzimidazole for example, N-(l-nbutylbenzimidazol-Z-yl)benzamide, N-(l-noctylbenzimidazol-Z-yl )benzamide, N-(lphenylbenzimidazol-Z-yl)benzamide, are prepared from theZ-aminobenzimidazole which is similarly substituted. The lattercompounds are easily prepared by methods known in the art.

Compounds having an acyl group at the N -nitrogen of the benzimidazole,for example, N-(l-nbutyrylbenzimidazol-Z-yl )benzamide, N-(lpivaloylbenzimidazol-2-yl) benzamide, N-( 1-stearoylbenzimidazol-2-yl)benzamide, N-(lacrylylbenzimidazol-Z-yl)benzamide, N-( l- Ibenzoylbenzimidazol-2-yl)benzamide, N-( l-p- 5toluylbenzimidazol-Z-yl)benzamide, N-(lmesitoylbenzimidazol-2-yl)benzamide, are prepared by reaction ofapproximately stoichiometric quantities of the2-carboxamidobenzimidazole and the appropriate acid chloride by gradualaddition of the acid chloride to a stirred mixture of the amide intetrahydrofuran containing an excess of triethylamine. The reactionmixture is maintained at room temperature for 4-8 hours. After removalof the solvent under reduced pressure, the residue is washed with water,filtered and dried.

The 2-aroylamino and 2- I heteroaroylaminobenzimidazoles may also besynthe-. sized from 2-methylthiopseudourea (preferably used as asulfate) by reaction of this latter material with an appropriate aroylor heteroaroyl halide. The reaction requires 2 moles of the acyl halidefor every mole of the pseudo-urea compound. It is generally broughtabout in E the presence of an acid binding agent or in an appropriv atesolvent medium such as dimethylformamide, di-

methylacetamide, and the like. The resulting 1,3-

diacyl-Z-methylthio-pseudourea is then reacted with o-phenylenediaminein order to obtain the 2-aroyl or Z-heteroaroylaminobenzimidazole. Anyof the acid;

chlorides used in the previous paragraph are'suitable for the reaction.This process is illustrated below, where R is defined as above:

n H f R -Q-Cl Base where R and substituents on the benzene ring of theimidazole are as above defined. Details of this reaction are given inExample 3, where the acid chloride is thenoyl chloride.

Another synthetic process for producing the com pounds disclosed hereincomprises the reaction of cy anamide with an essentially equimolaramount of an aroyl or heteroaroyl halide in pyridine or other solvent 15applicable for the preparation of the compounds uti to afford thecorresponding acylcyanamide. The resul- ;tant acylcyanamide is thenreacted with ophenylenediamine, whereby the desired 2-aroylamino or2-heteroaroylaminobenzimidazole is recovered and purified by knowntechniques. This process is illustrated as follows, where R,'is definedas above:

where R, and substituents on the benzene ring of the imidazole are aspreviously defined.

This process is particularly useful when substituents are present in thebenzene ring. The large variety of substituted-o-phenylenediamines whichare known in the art affords useful starting materials for this process.

Additional substituents can be introduced after formation of the2-aroylamino and 2- heteroaroylaminobenzimidazole. Reaction of the Nnitrogen in the benzimidazole moiety with alkylating and acylatingagents takes place readily. Substitution in the ring systems byconventional reactions such as nitration, halogenation, sulfonation andthe like may also be accomplished using known procedures.

Different substrates require varied UV-absorber solubility propertiesfor compatibility. A distinct advantage of the above definedZ-aminobenzimidazoles lies in the wide variety of compounds which can bemade. For example one skilled in the art can readily prepare effectivecompounds containing the key grouping as outlined above to obtain thenecessary UV aborption, along with highly-branched alkyl or carboxylgroups, the former to provide oil solubility and the latter, to provideaqueous solubility. Even strongly acid substituents such as sulfonicacid groups can be made part of the molecule by the conventionalsulfonation procedures. These can be introduced at the outset of asynthetic scheme; for example, the known 0- phenylenediamine substitutedwith a sulfonic acid grouping in the 3-, 4-, or 5-position can beconverted :to Z-aminobenzimidazoles containing the correspondingsulfonic acid group by known procedures. Subsequent reaction with aroyland heteroaroyl halides following the above procedures gives sulfonated2- aminobenzimidazoles which are water soluble at neutral or slightlyalkaline pH. They can be made oil soluble by reaction with organicamines. Metal salts of these compounds can be synthesized. For example,the

10 magnesium salt of N-(5-sulfobenzimidazol-2-yl)-4- chlorobenzamide isreadily prepared by treating with magnesium carbonate, to give a saltwhich can be incorporated in a UV-sensitive plastisol.

The general synthetic procedures outlined above are lized in thisinvention. However, when there are other substituents present containingactive hydrogen such as hydroxyl, amino or mercapto, for exampleblocking techniques may be needed to prevent acylation of these groups.These techniques are well known to those skilled in the art and comprisesuch reactions as the 0 the benzylated hydroxyl, amino or mercaptosubstituent by reduction with sodium in liquid ammonia, or catalyticallywith platinum and hydrogen. Corresponding acyl derivatives derived fromlower aliphatic acids are more readily hydrolyzable than theZ-aroylamino or heteroaroylamino groups and. can be selectivelysaponifled. These and other techniques, well known in the art, can beutilized.

Relatively strong acids are required to form salts With the 2-aroylaminoand the 2- 5O heteroaroylaminobenzimidazoles. Mineral acids such ashydrochloric, nitric, sulfuric, and phosphoric acids can be used, aswell as organic acids with sufficient acidity. These include, forexample, citric acid, salicy' clic acid, phthalic acid and lactic acids,either as dilute solutions or at very high concentrations. Quaternaryammonium salts can be made with methyl iodide, benzyl chloride, methylp-toluenesulfonate and the like. The alkaline salts can be prepared frominorganic bases or organic bases. Other salt-forming groups may bepresent as substituents on the benzene ring of the benzimidazole; theseinclude amino, alkyl-, aralkyl, and aryl-substituted-amino, or carboxyl.Similar substitution may be present on the aroyl and heteroaroylradicals at R When the aroyl moiety is substituted with a second aroylgroup, for example, N-(benzimidazol-Z- yl)-2-benzoylbenzamide, variousderivatives of the ketonic group can be utilized such as the oxime, thephenylhydrazone, semicarbazone, etc. The carbonyl of the benzoyl groupcomprising the ketonic portion can be hydrogenated to the alcohol, thatis, a benzhydrol derivative prepared, or the carbonyl can be condensedwith a second mole of Z-aminobenzimidazole or other amines.

The processes for synthesizing the N-(benzimidazol- 2-yl)-phthalimidesand the N,N'-bis(benzimidazol-2- yl)- phthalamides, isophthalamides andterephthalamides, as well as theN-(benzimidazol-Z-yl)alkoxycarbonylbenzamides derived therefrom areshown in Flow Sheet I.

Benzene polycarboxylic acid chlorides or annydrides such as phthalicanhydride or isophthalic acid, terephthalic acid or anhydro trimelliticacid chloride react with 2-aminobenzimidazole to form N-(benzimidazol-2-yl)phthalimide derivatives when there are two carboxy groups in orthoposition in the benzene ring, and N,N-bis(benzimidazol-2-yl)phthalamidederivatives when there are two carboxy groups in the meta or parapositions. (Compare compounds II, V, VIII and XI of Flow Sheet I). Allof these compounds are excellent 20 UV absorbers.

II c i o The phthalimide ring then can be opened by heating with analkanol so as to form the corresponding N- (benzimidazol-Z-yl )-2-(alkoxycarbonyl )benzamide (Compounds Ill, XIIA and XIIB). TheN-(benzimidazol-2-yl)-.3(or 4)-(alkoxy-carbonyl)-benzamides are preparedpreferably, by first converting the isophthalic acid or terephthalicacid to the alkoxycarbonyl benzoyl chloride, followed by reaction of thelatter compound with 2-amino-benzimidazole. (Compare compounds VI, IX,XIIA and XIIB). The latter compounds likewise show excellent propertiesas UV absorbers. Selective hydrolysis of the ester compounds (III, VI,IX, XIIA and XIIB) with alkali forms the salts ofN-(benzimidazol-Z-yl)carboxybenzamide. Acidification with dilute mineralacid to pH 3 yields the free carboxylic acid derivatives. Amine saltscan then be prepared by reacting the carboxylic acid with a slightstoichiometric excess of primary, secondary or tertiary amines such asmethylamine, ethylamine, diethylamine, triethylamine, and the like. Moredetailed information as to these processes is set forth in the examples.

phthalic acid (I) (II) (III) 0 o 0 II II -on ..c-mi-B :0R

H N-B (2 1&5)

mo -NIl-B C-NH-B2 O n 2 II 0 -o isophthalic acid (IV) (v) ,(V

o o I 0 II II I OH -NHB YJ-OR z v3 H2NB k I I Z K 2 on (2 moles) -NH-B7C-NIi-B II II ll 0 o o terephthalic acid (VII) (VIII) c' ((20 II2NBZ CN-B (2 moles) o o C-OH -C-NB II II 0 o trimellitic acid (XIIB) R alkyla(ben::imiclazol2-yl) group The benzene rinq of the hem:imidazolv orphthalic acid compound may be unsubstituted, or substituted by one ofthe qroups listed on page 3 The benzencring of the bcn zimidazol orphthalic acid compound may be unsubstituted, or substituted by one ofthe groups previously listed.

The benzene ring of the benzene polycarboxylic acid I of phthalimide,isophthalamide and terephthalamide have excellent compatibility,especially with the plastic materials made from the correspondingphthalic acid, for example, with the alkyd, Mylar, and Terylene resins(see The Merck Index of Chemicals and Drugs, Seventh Edition, 1960,MERCK & CO., Inc., Rahway, New Jersey, pages 698-699 and 1018,respectively).

The N-(benzimidazole-2-yl)phthalimides and phthalamides are alsocompatible with various plasticizers which are widely used in theplastics industry, in-

eluding compounds such as n-heptylphthalate, di-2-ethylhexylphthalate,butylnonylphthalate, or butylbenzylphthalate.

The efficiency of candidate chemicals as UV absorbers has been studiedin a variety of systems. Although accelerated tests are only indicatorsof potentially useful products, they serve to eliminate those compoundswhich themselves degrade on such exposure. One technique used involvesthe incorporation of the candidate chemical in a specific resin systemto produce a transparent film when cast on glass. The film is removedfrom the glass, stored for one week at ambient room temperature in thedark and then randomly distributed inches beneath a bank of threeWestinghouse RS sunlamps, 275 watts, for exposures. The equipment ismounted in a hood through which a flow of air is maintained across thefilms. A Colormaster differential colorimeter is used to measure colors;a white porcelain enamel color plate is used as the standard. Forcomparison purposes, films made from the same components but lacking theUV absorber candidate are utilized, one set being exposed identically tothe test specimens, and the other set stored away from light. The changein film color from initial to last exposure time is calculated fromcolorimetric measurements. One substrate used under these conditions isa moisturecured polyurethane prepolymer designated Spenkel 'MSO-SOCX(see SPENKEL Ms, Technical Service Bulletin, TS-6l93, l96l, SpencerKellog Division of Textron Inc., Buffalo, N.Y.). A series ofZ-amidobenzimidazoles of this invention are weighed into this prepolymerand agitated until dissolved, the flasks being covered with aluminumfoil for protection from light during this procedure. The polyurethaneprepolymer is then east as a 3-mil wet film on clean dry glass plates,using a Bird film applicator. The plates are then stored in the cabinetwith ventilation, but protected from light, and the films allowed tocure for one week at ambient temperature and humidity. Approximately /2mil films result. The exposure then to the UV-light is run for varyingperiods of time. Within 1 week, using varying levels of UV-lightabsorber, it is possible to distinguish between compounds which arecapable of protecting the polymer system from extreme yellowing andthose which fail. Comparisons are made, for example, between2-(o-hydroxyphenyl)benzotriazole and the 2- amido-benzimidazoles. Underthese conditions of test, 2-amido-benzimidazole compounds show similarprotective capabilities without the inherent drawbacks whichcharacterize the hydroxyphenyl-substituted benzoheterocyclicderivatives.

The UV absorbing compounds of the present invention are used for controlof deterioration of a UV sensitive substance by ultraviolet light. Thereare several fields of application, for example:

1. The UV absorber may be incorporated in an ultraviolet sensitivecomposition especially a plastic, to protect it from discoloration,impairment of tensile strength, embrittlement or other deleteriousreactions caused by ultraviolet rays. The: UV absorber may beincorporated in the plastic composition before, during, or subsequent tothe manufacture of the latter by way of a suitable operation.

2. The UV absorber may be incorporated in a composition to protect aningredient thereof, for example, a dye, plasticizer or antimicrobialagent from attack by ultraviolet light.

3. The UV absorber may be incorporated into a composition to protect anunderlying substratum to which the composition is to be applied from theattack of ultraviolet rays, e.g. use in suntan lotions or creams toprotect the skin.

In a preferred embodiment of this invention, a plastic material isstabilized against deterioration caused by ultraviolet light, by havingincorporated therein an effective amount of a 2-aryl(orheteroaryl)carboxamidobenzimidazole as a UV absorber. The plasticmaterial to which the UV absorber is added may be in any conventionalform such as a sheet, film, coating or fiber.

Practically all plastics undergo degration by prolonged exposure to UVradiation, especially in the region of 300-350 millimierons. Thedeleterious results may result in objectionable yellowing of theplastic, cracks, diminished mechanical strength properties, and thelike. Table II indicates the areas of sensitivity to UV of severalcommon plastics.

Table ll Wavelength (m J.) of

Synthetic Plastics Maximum Sensitivity Polyethylene 300 Polypropylene(non-heat stabilized) 3 l0 Polyvinyl chloride 310 Polystyrene Polyvinylchloride copolymer with vinyl acetate Polyesters (various formulations)318 322 and 364 trile), Dynel (copolymer of acrylonitrile and vinylchloride), Acrilan (polyacrylonitrile modified with vinyl acetate) [seeMERCK INDEX, Seventh Edition, 1960, pages 740, 786, 1018, 757, 395 and17 respectively]Saran (copolymer of vinylidine chloride and vinylchloride), [see HACKHS CHEMICAL DICTIONARY, Third Edition, 1944,McGraw-Hill Book Company, Incorporated, New York, N.Y.], and the like.

The UV absorbing compounds of this invention are incorporated in plasticfilms by methods known in the art. Heat-stabilized polyvinyl chloridefilms are protected very simply by the addition of the2-amidobenzimidazole prior to extrusion of the film. In a conicalshapeddry-powder, blender, 98 parts of a copolymer of 75 parts vinylidenechloride and 25 parts vinyl chloride are mixed with 2 parts on N-(5-chlorobenzimidazol-Z-yl)benzamide and extruded to produce a clear film.This film completely blocks out the deleterious energy. WhenUV-light-sensitive paper is placed under such treated film, nodiscoloration is produced. in comparison, untreated polyvinyl chloridefilm permits sufficient UV-light energy transmission to cause, a severeyellowing. Similarly, when 5 parts of N-(5,6-dimethylbenzimidazole-2-yl)benzamide is dryblended with apolystyrene powder, obtained from commercial sources, and the mixtureformed into sheets by extrusion in the usual way, UV-light screeningfilms are thereby obtained.

Polyvinyl chloride plastic compositions stabilized against ultravioletlight by the UV absorbers of this invention are used in the form ofsheeting for automotive upholstery, as films for shower curtains, asextrusions for window blinds, and as a plastisol for casting or coating.

A typical formulation for the extrusion of window blinds is as follows:polyvinyl chloride, 100 parts; phthalate ester of long-chain aliphaticacid, 67 parts; tricresyl phosphate, Sparts; polymeric resin, 5 parts;stabilizer/lubricant, one-half part; titanium dioxide, 4 parts; calciumcarbonate, 25 parts; and stearic acid, 0.25 part. To this resin mix isadded the UV-stabilizer, such as 2-benzamidobenzimidazole, at a generallevel of 1.75 parts. The ingredients are dry-blended and then extrudedat fusion temperatures. Without the presence of an effectiveUV-absorber, the effects of UV- degradation would be to causediscoloration, brittlement and, finally, serious loss of mechanicalstrength. Similarly, sheeting and film must have UV-absorber additionwhen use-conditions cause exposure to such radiation. Calcium carbonateis an essential part of all polyvinyl formulations and calcium carbonatecan cause discolorations with the hydroxyphenylsubstituted UV-absorbersof the prior art. It is an advantage of the present invention that anyhydrogen chloride which may be generated from the breakdown of polyvinylchloride would have no adverse effects upon the 2-amidobenzimidazoles.

Vinyl sheeting is also used as a surfacing agent over plastic panelswhich form a part of illumination ceiling structures. Indoors,fluorescent lights are emitters of sufficient UV-light to causepremature aging and discoloring of plastics. Incorporation of theUV-absorber in the resin or in the film serves to minimize this damage.

Cellulose films are made, for example, using 270 parts by weight ofalkali cellulose derived from 77 parts of cellulose, 24.3 parts ofcarbon disulfide and 17.5 parts of sodium hydroxide. The carbondusulfide is added in one portion and the mixture is agitated in asuitable dough mixer at about 20C. for 22 hours. After xanthation iscomplete, the resulting mixture is diluted with 595 parts of water. Atthis stage, the 2-substitutedamidobenzimidazole is added and mixed untildissolved or completely dispersed. Resultant solutions are then aged atca. 5C. Next, vacuum is applied to remove air bubbles from the solution,and the material is regenerated in film form in the usual manner byextrusion through a slit into an aqueous bath containing 10% sul furicacid; 1% zinc sulfate, 14% sodium sulfate, 10% glucose and the balance,water.

The compounds of this invention are also added to a moisture-proofcoating (lacquer) of the regenerated cellulose film as well as to thesubstrate. Solutions of the 2-amidobenzimidazoles can be added to thelacquer solution so that upon solvent evaporation a residualconcentration of l5% of the 2- amidobenzimidazole is contained in thelacquer film. Removal of the solvent by warm air drying does notvolatilize nor discolor the compounds. When used in such concentrationsas indicated, there is complete blocking of UV-light transmission from arange of 290-390 millimicrons. When clarity of the film is of utmostimportance to its end-use, it is preferable to employ the more soluble2-amidobenzimidazoles, for example, N-( benzimidazol-2-yl )-4-carboethoxybenzamide or N-(bezimidazol-2-yl)-4-methoxybenzamide.

Polyethylene is used to coat many substrates in a technique whichconsists of dusting on finely-powdered polyethylene to a moving belt ofthe material to be covered, for example, textiles, tarpaulins, or evenmetals. The substrate containing a layer of finely-divided poly ethyleneon the surface speeds through a heating tunnel or oven which ismaintained just above the fusion temperature of the polyethylene, sothat a thin liquid layer forms. From the oven the material passesthrough a nip roll and chill roll combination for both thoroughlyspreading the liquid film over the entire surface and then causingsolidification. The polyethylene coating thereby achieved needsprotection against UV- degradation. ln those applications where opaquematerials cannot be tolerated, this can be readily accomplished bypre-mixing in ribbon or conical powder blenders from 0.2-2% ofN-(benzimidazol-Z-yl)-4-tbutylbenzamide. The 2-amidobenzimidazole isfinely divided to the same particle range as the polyethylene, prior tomixing. The mix is then fed from the hopper to the moving belt formed bythe substrate. The compounds of this invention are suitable for suchapplication because of their non-volatility and heat stability, alongwith compatibility with the resin system, especially in the moltenstate.

Clear gloss exterior finishes are used as top coats over wood, masonry,metal and other substrates to provide a durable coating. in typicalformulation, the clear finish is prepared from two parts. One componentis the clear base which is made by dissolving 278 lbs. of anoxirane-modified ester resin in lbs. of a light petrolum solvent and28.7 lbs. of ethylene glycol ethyl ester acetate. The second componentis the clear activator. It consists of 417 lbs. of polyester solution,50 lbs. of 15% cellulose acetate butyrate solution and 29.6 lbs. ofethylene glycol ethyl ether acetate to which is added 1 15 lbs. ofN-(benzimidazol-2-yl)-4- methoxybenzamide. The clear finish is made bymixing 406.7 parts of part one clear base with 511.6 parts of the clearactivator (part two). The UV-absorber conccntration, based on resinsolids, is about 3.0% by weight.

Nylon-type resins are used in the manufacture of fibers for carpeting,hoisery, garments and the like. The resins are melted in an inertatmosphere and at temperatures of 230275C., and then extruded throughspinnerets. The melting of the resin is done in a batch oper ation; heatexposure is of such duration that only the most stable additives can beemployed successfully by addition to the resin melt. The2-amidobenzimidazoles are extremely stable to elevated temperatures andcan be incorporated in the melt at levels from 0.25% prior to extrusion.The need for UV protection in the resin systems is especially apparentwhen other additives such as antimicrobial agents or dyes are alsopresent. N,N-bis(benzimidazol-2-yl)terephthalamide is unaffected bytemperatures up to 340C. Other resin systems for which this agent findsparticular utility are the polyesters derived from terephthalic acid andpolyeth ylene glycols.

These, too, are used as fibers for textile application as well ascarpeting and the like. For this purpose the Z-amidobenzimidazoles arefinely powdered and then blended with Nylon-6 powder at room temperaturein the ratio of 0.3 part of the benzimidazole to 99.7 parts Nylon. Thepowder is then heated gradually in a nitrogen atmosphere; at 225C.melting begins and the mix finally becomes a water-white liquid. Themelt could be brought to temperatures as high as 270C. for spinning intofiber or for use in molding operations.

in another embodiment of this invention the UV absorber is incorporatedin a composition to protect an ingredient thereof from attack byultraviolet rays. Organomercurial salts, for example, phenylmercuryacetate, propionate and oleate, are widely used to protect suchvulnerable substrates as coatings and plastics from microbialdeterioration. These mercurials are degraded rapidly upon exposure toultraviolet radiation. They are used in concentrations of from aboutODS-0.5% by weight, especially in substrates which are for use outdoors.Transparent sheeting containing such antimicrobial agents must have UVabsorbers incorporated to protect not only the plastic sheeting but alsothe microbial inhibitor from light deterioration. Usually from about 0.1to about 0.5% by weight of a 2- carboxamidobenzimidazole, for example,will impart such a protective action.

Similarly, vinyl fabric used on outdoor furniture undergoes a shorteneduseful life unless not only the antimicrobial agent but also theplasticizers contained therein are protected against UV. It is knownthat dialkyl phthalate and other well known and commonly used esterscannot withstand absorption of UV energy without degradation.

In still another embodiment of this invention the UV absorber isemployed for those uses where a composition is applied to a substratethat is normally subject to deterioration by ultraviolet light. Forexample, in comestibles, of which more or less temporary protection isdesired, the material is enclosed with a transparent plastic wrappingcontaining the UV absorber which serves as a filter for the harmfulrays. Another example of a use of this type is in lacquers, clearcoatings and paints for wood and the like.

Suntan screening preparations commonly in use on human skin generallymust perform satisfactorily for periods of less than 24 hours.Re-application of the formulation must be made on subsequent exposuredays because of prior removal by washing or bathing. A stable and usefulpreparation consists of the following:

Chemical Parts By Weight (n-butoxycarbonyl )benzamide 0.5 Polyethyleneglycol. m.w. 300 42.5 Propyleneglycol 25.0 lsopropyl myristate 2.5Ethanolquinine 29.2 Perfume 0.03

The formulation is applied either by lightly dabbing the skin orspraying.

The UV absorber may also be incorporated in a suntan formulationcontaining insect repellents, for exam ple:

Chemical Parts By Weight ethoxycarbonyl)benzamide 0.5 Adipic acidisopropyltetrahydrofurfuryl ester 14.5 Metatoluic acid diethylamide 5.0Phthalic acid dimethyl ester 8.0 Groundmut oil 36.0 Paraffin Oil 36.0

The formulation can be applied by lightly rubbing into the skin forachieving both effects, that is screening of UV-light and the repellingof insects.

The N-(benzimidazol-Z-yl)benzamides are also useful for protectinghair-setting and hairgrooming gels. These preparations can containthickening or gelling agents which are amine salts of resin carboxylicacids. Some of the amines employed are di(2-ethylhexyl)- amine anddi(isopropanol)amine. Lanolin, fatty acid esters and ethoxylated lanolinare also components of the formulations. Generally, about 0.2% to 0.5%by weight of the UV absorber is required.

The following examples are given for the purpose of illustration and notby way of limitation.

EXAMPLE 1 N-( Benzimidazol-Z-yl )-4-tert-butylbenzamide A mixture of 18g. of p-tert-butylbenzoic acid and 25 g. of thionyl chloride arerefluxed 1 hour. The thionyl chloride is strippped under reducedpressure, and to insure complete removal, two 50 ml. portions of benzeneare added successively and stripped. The liquid residue is distilledunder reduced pressure and the colorless liquid boiling at C. at 2.2 mm.pressure is collected; yield 15.7 g.

2-Aminobenzimidazole (10.7 g.) is dissolved in 100 ml. of dry pyridine,mixed with l5.7g of p-tert butylbenzoyl chloride and heated for 1 H2hours on a steam bath. The mixture is cooled to room temperature andpoured into 600 ml. of water; the precipitated product is removed bysuction filtration, washed well with water and dried under vacuum at60C. The yield of crude product is 22.5 g. It is recrystallized from asmall volume of glacial acetic acid containing 1 ml. of water for each15 ml. of acid. Long colorless needles are thereby obtained, m.p.246-248C., )tmax. 302 ,u., E 17c cm. 737.

In accordance with the above procedure, but using an equivalent quantityof p-methoxybenzoyl chloride, p-methylbenzoyl chloride oro-fluorobenzoyl chloride in place of p-tert-butylbenzoyl chloride thereis ob- 19 tained as a product N-(benzimidazol-2-yl)-4- methoxybenzamidc,N-(benzimidazol-2-yl)-4- methylbenzamide, or N-(benzimidazol-2-yl)-2-fluorobenzamide, respectively.

Following the above procedure. using as reactants benzoyl chloride andequivalent quantities of 2-amino- -dodecyloxybenzimidazole, 2-amino-4-phenylbenzimidazole, 2-aminol nbutyl )benzimidazole, 2-amino- 1-phenylbenzimidazole, or 2-amino-1-(methoxycarbonyl)benzimidazole, thereis obtained as a product, N-(S-dodecyloxybenzimidazol-2-y1)-4-benzamide, N-(4-phenylbenzimidazol-Z-yl)-4-benzamide, N-( l-n-butyl)benzimidazol-Z-yl)-4-benzamide, N-( 1-phenyl)benzimidazol-2-yl)-4-benzamide, orN-(lmethoxycarbonyl)benzimidazol-2-yl)-4-benzamide, respectively.

EXAMPLE 2 2-(Thiazole-4-carboxamido )benzimidazole 2-Aminobenzimidazole(6.7 g.) is dissolved in 50 ml.

of pyridine and reacted with 8.0 g. of thiazole-4- carboxylic acidchloride by heating on a steam bath for 3 hours. The cooled reactionmixture is poured into 200 ml. of water, stirred for one hour and thensuction filtered. The product is purified by solution in hot alcohol,filtration from a small amount of insolubles and gradual cooling. Thecompound melts at 294-296C., Amax. 303 11., E 1% cm. 790.

Substitution of an equivalent amount of other heterocyclic acidchlorides, e.g., pyridine 2-, 3-, and 4- carboxylic acid chlorides;theonyl 2- and 3-chlorides, coumariloyl chloride forthiazole-4-carboxylic acid chloride provides a convenient synthesis for:2- (pyridine-Z-carboxamido)benzimidazole, 2-(pyridine-3-carboxamido)benzimidazole, 2-(pyridine-4-carboxamido)benzimidazo1e,2-(thiophene-Z-carboxamido)- benzimidazole, respectively. 2-(coumariloyl)aminobenzimidazole, m.p. 293295C. A

max. 327 mu, E cm. 1024 and 2- nicotinamidoaminobenzimidazole, max. 319m,u., lllllr EXAMPLE 3 2-(2'-Thenoyl)aminobenzimidazole A suspension of5.56 g. (0.02 mole) of 2- methylthiopseudourea sulfate, 4.0 g. (0.04mole) triethylamine and 50 ml. of dimethylformamide is cooled to 0C. andtreated with a solution of 5.88 g. (0.04 mole) of Z-thenoyl chloride inml. of dimethylformamide. The reaction mixture is allowed to warm toroom temperature, stirred for 2 hours and is then poured onto 500 g. ofan ice-water mixture. The colorless solid product is separated byfiltration and washed with water. This solid is recrystallized fromethanol to give l,3-dithenoyl-2-methylthio-pseudourea, m.p. l66167C.

A solution of 1.55 g. (0.01 mole) of 1,3-dithenoyl-2-methylthio-pseudourea and 1.08 g. of ophenylenediamine in 50 ml. ofethanol is refluxed for 5 hours. The solid is then removed in vacuo andthe residue is recrystallized from ethanol. The yield is substantiallypure 2-(2'-thenoyl)aminobenzirnidazole, m.p. 303305C.

When thiazole-4-carbonyl chloride or picolinyl chloride is employed inthe above process in place of thenoyl chloride. there is obtained2-(4'-thiazoly1carbonyl) aminobenzimidazole or 2-( 2 picolinoyl)aminobenzimidazole, respectively.

EXAMPLE 4 4-Methyl-2-benzoylaminobenzimidazole Cyanamide (3.44 g.) isdissolved in 69 ml. of pyridine and the mixture is held at 0-4C. Whilestirring, benzoyl chloride (11.5 g.) is added in portions. The reactionmixture is maintained at 0-4C. for 15 minutes.3-Methyl-o-phenylenediamine (10 g.) is then added to the reactionmixture, and the resulting product is kept at room temperature for a fewhours and then heated on a steam-bath for about 2.5 hours. After coolingto room temperature. the mixture is evaporated under reduced pressure,poured into 200 ml. water, and rubbed until solid. The product isremoved by suctionfiltration, dissolved in 5% aqueous sodium hydroxidesolution, and clarified by gravity filtration. The benzimidazolederivative is precipitated by the addition of the alkaline solution to aslight excess of dilute acetic acid.

EXAMPLE 5 5-Chl0ro-2-(2-furoy1)aminobenzimidazole5-Chloro-Z-aminobenzimidazole (5.0 g., 0.03 mole) and 2-furoy1 chloride(3.9 g., 0.03 mole) is mixed in 25 ml. of pyridine and heated for 2hours on the steam bath. It is then cooled to room temperature, pouredinto 250 ml. of water, mixed one-half hour and then suction filtered. Ayield of 7.3 g. is obtained. The product is purified byrecrystallization from a aqueous solution of acetic acid. On drying atC. and 1 mm. pressure for 12 hours, it is obtained as an acetic acidsolvate, m.p. 249-251C., corresponding to the empirical formula C H N OCLCH COOH. On further drying the sample at C. and 1 mm. for 4 hours, theacetic acid is removed, m.p. 250251C., )tmax. 310 1.1., E 17: cm. 938.

Similarly 2-(Z-furanacrylyl)aminobenzimidazole, m.p. 250-251C., Amax.329 ,LL, E 17ccm. 1477 is obtained by reaction of an equivalent quantityof 2- furanacrylic acid with 2-aminobenzimidazole.

EXAMPLE 6 2-( 5 -tert-butyl-2 -fur0yl)aminobenzimidazoleS-Tert-butyl-Z-furoic acid chloride is prepared from the correspondingfuroic pand thionyl 11% cm. the method of H. Gilman and N. O. Calloway,J. Am. Chem. Soc., 55, 4197-4205 (1933). 7.1 G. of S-tertbutyl-2-furoylchloride and 5.1 g. of 2- aminobenzimidazole are reacted in 35 ml. ofpyridine by heating on a steam bath for 2 hours. The reaction mixture iscooled to room temperature and poured into 250 ml. of water, stirred 15minutes and then suction filtered. A yield of 10.9 g. is obtained. Theproduct is recrystallized from acetic acid containing 30% of water. Longcolorless needles are obtained, as an acetic acid solvate, which meltsat 257258C. A sample dried at 80C. at 1 mm. pressure for 16 hours stillretained the acetic acid. It is then dried for 4 hours at 130C. at 0.1mm. for removal of the acetic acid. The compound then melts at257.5259C., Amax. 312 mp, E 956.

In accordance with the above procedure but starting with theappropriately substituted Z-furoyl chloride. the following products areobtained: 2-(5'-phenyl-2'- furoyl)aminobenzimidazolc. m.p. 247248.5C.,

)tmax. 334 [.L, E l'7z cm. 1245 and 2-(5'-benzoyl2'-furoyl)aminobenzimidazole, m.p. 26927lC., )lmax. 345 u, E l% cm. 785.

EXAMPLE 7 N-(Benzimidazol-2-yl)-2-(n-butoxycarbonyl)benzamide (Ill)Z-Aminobenzimidazole (13.3 g.) is dissolved in 50 ml. of pyridine, and10.2 of phthaloyl chloride is added, causing immediate precipitation. Onmixing and heating on the steambath, all dissolves. The solution isheated two hours on the steam-bath with occasional swirling, It iscooled to room temperature and quenched in 200 ml. of water. After onehour agitation, the mixture is filtered free of solids and the solidswashed with water. The yield of N-(benzimidazol-2- yl)phthalimide is11.6 g. Recrystallization from glacial acetic acid results in brightyellow crystals of N-(benzimidazol-2-yl)phthalimide which, after drying,melts at 266-268C., )tmax. 295.0, E 1% cm. 529.

N-(Benzimidazol-Z-yl)phthalimide (4 g.) in 200 ml. of n-butyl alcohol isheated at 115C. for 35 minutes. On cooling, colorless needles form.These are removed by suction filtration, washed with butyl alcohol andfinally with diethyl ether. After drying for 3 hours at 125C. undervacuum, a yield of 2.5 g. of N- (benzimidazol-2-yl)-2-( n-butoxycarbonyl)-benzamide, m.p. 187C., is obtained. Additional heating to highertemperatures causes a reclosure to the phthalimide and remelting whichcorresponds to the phthalimide, m.p. 267268C.

Other esters such as the methyl, propyl, and higher alkyl derivativesare prepared from the N-(benzimidazol-Z-yl)phthalimide using methanol,propanol, or higher alkanols in place of butyl alcohol. In this man ner,the following compounds are prepared: N-(benzimidazol-Z-yl)-Z-methoxycarbonylbenzamide, N-( benzimidazoLZ-yl)-2-isopropoxycarbonylbenzamide, andN-(benzimidazol-Z-yl)-2-dodecycloxycarbonylbenzamide.

Replacement of Z-aminobenzimidazole in the first step with an equivalentweight of ring-substituted 2- aminobenzimidazole, followed by reactionwith the phthaloyl chloride, gives N-(substituted-benzimidazol-2-yl)phthalimide. This compound is then converted to the corresponding(2-alkoxycarbonyl)benzamide by the procedures outlined. The followingcompounds are prepared according to this method: N-(S-chlorobenzimidazol-2-yl 2-methoxycarbonyl )benza- 'mide using5-chloro-2-aminobenzimidazole in Step 1 .and methanol in Step 2;N-(5,o-dimethylbenzimidazol- 2-yl 2-n-butoxycarbonyl )benzamide from5,6- dimcthyl-Z-aminobenzimidazole in Step 1 and nbutanol in Step 2;N-(5-acetamidobenzimidaz0l-2-yl)- (Z-n-isopropoxycarbonyl) benzamidefrom 5- acetarnido-2-aminobenzimidazole in Step 1 and isopropanol inStep 2; N-( 1-butylbenzimidazol-2-yl)-(2- methoxycarbonyl )benzamidefrom l-buty1-2- aminobenzamidazole in Step 1 and methanol in Step 2.

Similarly, replacement of phthaloyl chloride with an equivalent weightof substituted phthaloyl chloride, followed by reaction withZ-aminobenzimidazole, forms the corresponding phthalimides in Step 1.These are reacted as described in Step 2 with alcohols to form thecorresponding substituted (2-alkoxylcarbonyl)benzamides. Typicalcompounds prepared by this method are: N-( benzimidazol-2-yl2-methoxycarbonyl )-5 phenylbenzamide, N-(4-methylbenzimidazol-Z-yl 2-EXAMPLE 8 N,N-bis(benzimidazol-2-yl)-isophthalamide (V)2-Aminobenzimidazol 13.3 g.) is dissolved in 50 ml. of pyridine andreacted with 10.2 g. of isophthaloyl chloride. Complete solution isobtained initially and after 1% hours of heating on the steam bathabundant solids are evident. The mixture is cooled to room temperatureand dumped into 250 ml. of water. After one hour of agitation, theproduct is removed by suction filtration. It is purified byrecrystallization from glacial acetic acid. The yield of crude productis 14.6 g. The purified compound does not melt at temperatures up to320C. and there are no visible: signs of decomposition during thisheating. The product shows Amax. 319, E,l% cm. 950.

Replacement of Z-aminobenzimidazole with an equivalent amount of5,6-dimethylbenzimidazole followed by reaction with isophthaloylchloride gives N,N- '-bis-( 5 ,6-dimethylbenzimidazole-2-yl)isophthalamide.

EXAMPLE 9 N,N-bis-( benzimidazol-Z-yl)terephthalamide (VIII)2-Aminobenzimidazole (13.3 g.) and 10.2 g. of terephthaloyl chloride in50 ml. of pyridine is heated on a steam bath for a total of 4 hours. Inthe first 15 minutes of reaction an additional 25 ml. of pyridine isadded. The mixture is cooled to room temperature and poured into 300 ml.of water, mixed 1 hour and the product removed by suction filtration.The product is purified by recrystallization from dimethylformamide towhich a small volume of water is added. The compound melts above 340C.,Amax. 334, E,l% cm. 871.

Replacement of Z-aminobenzimidazole with an equivalent amount of5-chlorobenzimidazole, followed by reaction with terephthaloyl chloridegives N,N'- bis( 5 -chlorobenzimidazol-2-yl )terephthalamide.

EXAMPLE 10 N-( Benzimidazol-2-yl)-4-(ethoxycarbonyl )benzamidep-Ethoxycarbonylbenzoyl chloride is prepared according to the method ofM. J. Dewar and J. P. Schroeder, J. Org. Chem., 30, 2297 (1965), by thegradual addition of a small amount of ethyl alcohol to a boilingsolution of terephthaloyl chloride in benzene. After removal of thesolvent the residue is distilled under reduced pressure to give the acylchloride which boils at l02-l05C. at 0.4 mm.

2-Aminobenzimidazole (9.8 g.) is dissolved in ml. of pyridine andreacted with 16.3 g. of pcthoxycarbonyl chloride by heating on a steambath for 3 hours. The cooled mixture is poured into 600 ml. of water,agitated 1 hour and the product removed by suction filtration. It isthen washed well with water and dried. A yield of 20.7 g. is obtained.It is purified by re crystallization from ethyl alcohol to givecolorless needles, m.p. 224225.5C., Amax. 322.5, E l% cm. 613.

Selective hydrolysis of the ester with 5-107c aqueous 'sodium hydroxidesolution forms N-(benzimidazol-2- yl)-4-carboxybenzamide, sodium salt.Acidification bonyl )-1 ,4( 3 )-phthalamide with dilute mineral acid topH 3 yields the 4-carboxylic acid derivative. Amine salts can then beprepared by reacting the carboxylic acid derivative with a slightstoichiometric excess of primary, secondary or tertiary amine.

In accordance with the above procedures, but starting' with the knownp-methyl-, p-(n-propyl), p-(n- 4 butyl), p-(n-amyl) or p-(n-decyl) esterof benzoyl chloride, the corresponding N-benzimidazol-2-yl)-4-(alkoxycarbonyl)benzamide is obtained.

EXAMPLE 11 N-( Benzimidazol- 2-yl )-4-(benzimidazol-Z-ylcarbonyl)-phthalimide (XI) Anhydrotrimellitic acidchloride (ll g.) is mixed with 13.3 g. of Z-aminobenzimidazole in 75 ml.of pyridine. A clear solution results on heating on the steam bath;after 3 hours, the reaction contains appreciable solids. The mixture iscooled to room temperature, poured into 400 ml. of water, agitatedone-half hour and the product removed by suction filtration. A yield of16.6 g. is thereby obtained. The product is purified byrecrystallization from dimethylformamide. It is dried at 130C. at 0.1mm. pressure, m.p. 352353C. Elemental analysis agrees with respect tocarbon, hydrogen, and nitrogen for the formula C ,,H N O of a compoundof having the structure XI of Flow Sheet I.

The above phthalimido compound is heated with nbutyl alcohol followingthe procedure of the second step of Example 10 to open up thephthalimido linkage and give the corresponding n-butoxy compound, whichis N,N'-bis-(benzimidazol-2-yl)-3 or (4)-(n-butoxycar- (Compound XllA orXXlB). Any departure from the above description which conforms to thepresent invention is intended to be included within the scope of theclaims.

What is claimed is:

1. A method for controlling the deteriation of a UV sensitive substanceby ultraviolet light which comprises contacting the UV sensitivesubstance to be protected with an ultraviolet absorbing effective amountof a N- (benzimidazol-Z-yl)arylcarboxamide selected from the groupconsisting of a. N-(benzimidazol-Z-yl)arylcarboxamides the formula:

having b. a N-(benzimidazole-Z-yl)arylcarboximide derived from a benzenepolycarboxylic acid selected from the group consisting ofN-(benzimidazoLZ- yl)phthalimide, N,N-bis(benzimidazol-2- yl)isophthalamide, N,N-bis( bcnzimidazol-Z- yl)terphthalamide andN-(benzimidazol-2-yl)-4- (benzimidazol-2-yl-carbonyl )-phthalamidewherein R, is carbocyclic or heterocyclic aryl radical selected from thegroup consisting of phenyl biphenyl, naphthyl, anthryl, phenanthryl,furyl, thienyl, pyridyl, pyridazyl, pyrimidyl, pyrazinyl, quinolyl,isoquinolyl, acrydyl, phenanthridyl,

0 (I) and phenazyl, phenoxazyl, phenthiazyl, coumaronyl,

benzothienyl, indolyl, pyrazolyl, imidazolyl, thia zolyl, oxazolyl,triazolyl, and carbazolyl, attached to the carbonyl group directly orthrough a (Ch=CH) group;

R is a member selected from the group consisting of hydrogen, alkanoyl,alkenyl, benzoyl, halobenzoyl, alkoxybenzoyl, alkoxycarbonyl, alltyl andphenyl; and

wherein the ring of said benzimidazole, benzine polycarboxylic acid andthe carbocyclic or heterocyclic aryl radical present at R, may beunsubstituted or substituted by one or more members selected from thegroup consisting of alkyl, alkenyl, phenyl, chloro, nitro, hydroxy,alkoxy, phenoxy, naphthoxy, amino, alkylamino, dialkylamino,phenylamino, phenalkylamino, sulfo, carboxy, alkoxycarbonyl,alkylcarbonyl and phenylcarbonyl.

2. The method according to claim 1 wherein the R, substituent of the UVabsorbing compound having formula I is a member selected from the groupconsisting of phenyl and phenyl substituted at the 2-, 3- or 4- positionby a member selected from the group consisting of alkoxycarbonyl,carboxy, phenyl, nitro andcarboxamdio, and when the substituent is acarboxy group, the salts thereof with primary, secondary and tertiaryalkyl amines.

3. The method according to claim 1 wherein the R, substituent of the UVabsorbing compound having formula I is a heterocyclic aryl radicalselected from the group consisting of furyl, thienyl, pyridyl,pyridazyl, pyrimidyl, pyrazinyl, quinolyl, isoquinolyl, acrydyl,phenanthridyl, phenazyl, phenoxazyl, phenthiazyl, coumaronyl,benzothienyl, indolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl,triazolyl, and carbazolyl.

4. The method according to claim 1, wherein said UV absorbing compoundmember selected from the group consisting ofN-(benzirpidazol-Z-yl)phthalimide, N,N-bis-(benzimidazol-Z-yl)isophthalamide, N,N- bis(benzimidazol-2-yl)-terphthalamide N- (benzimidazol-Z-yl)-4-(benzimidazol-2-ylcarbonyl)phthalimide, the benzene rings of which compounds are unsubstituted orsubstituted by one or more members selected from the group consisting ofalkyl, alkenyl, phenyl, chloro, nitro, hydroxy, alkoxy, phenoxy,naphthoxy, amino, alkylamino, dialkylamino, phenylamino,phenylalkylamino, sulfo, carboxy, alkoxycarbonyl, alkylcarbonyl andphenylcarbonyl.

5. The method according to claim 1 wherein said UV absorbing compoundhas the formula:

and

N LN i: (CH=CH) R1 tuted by one or more members selected from the groupconsisting of alkyl, alkenyl, phenyl, chloro, nyl. nitro, hydroxy,alkoxy, phenoxy, naphthoxy, 6. A method according to claim 1 wherein theN- amino, alkylamino, dialkylamino. phenylamino,(benzimidoal-Z-yl)arylcarboxamide is N- phcnylamino, phenylalkylamino,sulfo, carboxy, (benzimidazol-Z-yl)-4-t-butylbenzamide. alkoxycarbonyl,alkylcarbonyl and phenylcarbo- 5

1. A METHOD FOR CONTROLLING THE DETERIATION OF A UV SENSITIVE SUBSTANCEBY ULTRAVIOLET LIGHT WHICH COMPRISES CONTACTING THE UV SENSITIVESUBSTANCE TO BE PROTECTED WITH AN ULTRAVIOLET ABSORBING EFFECTIVE AMOUNTOF N-(BENZIMIDAZOL-2-YL)ARYLCARBOXAMIDE SELECTED FROM THE GROUPCONSISTING OF A.N-(BENAIMIDAZOL-2-YL)ARYLCARBOXAMIDES HAVING THEFORMULA:
 2. The method according to claim 1 wherein the R1 substituentof the UV absorbing compound having formula I is a member selected fromthe group consisting of phenyl and phenyl substituted at the 2-, 3- or4- position by a member selected from the group consisting ofalkoxycarbonyl, carboxy, phenyl, nitro and carboxamdio, and when thesubstituent is a carboxy group, the salts thereof with primary,secondary and tertiary alkyl amines.
 3. The method according to claim 1wherein the R1 substituent of the UV absorbing compound having formula Iis a heterocyclic aryl radical selected from the group consisting offuryl, thienyl, pyridyl, pyridazyl, pyrimidyl, pyrazinyl, quinolyl,isoquinolyl, acrydyl, phenanthridyl, phenazyl, phenoxazyl, phenthiazyl,coumaronyl, benzothienyl, indolyl, pyrazolyl, imidazolyl, thiazolyl,oxazolyl, triazolyl, and carbazolyl.
 4. The method according to claim 1,wherein said UV absorbing compound member selected from the groupconsisting of N-(benzimidazol-2-yl)phthalimide,N,N-bis-(benzimidazol-2-yl)isophthalamide, N,N-bis(benzimidazol-2-yl)-terphthalamide andN-(benzimidazol-2-yl)-4-(benzimidazol-2-yl-carbonyl)phthalimide, thebenzene rings of which compounds are unsubstituted or substituted by oneor more members selected from the group consisting of alkyl, alkenyl,phenyl, chloro, nitro, hydroxy, alkoxy, phenoxy, naphthoxy, amino,alkylamino, dialkylamino, phenylamino, phenylalkylamino, sulfo, carboxy,alkoxycarbonyl, alkylcarbonyl and phenylcarbonyl.
 5. The methodaccording to claim 1 wherein said UV absorbing compound has the formula:6. A method according to claim 1 wherein theN-(benzimidoal-2-yl)arylcarboxamide isN-(benzimidazol-2-yl)-4-t-butylbenzamide.